Wood preservation



Patented May 20, 1930 UNITED STATES PATENT OFFICE EDWARD S. MOQUAID, 01? LAKEWOOD, OIIIO, ASSIGNOR '10 HAROLD W. WALKER, OI EDGEWOOD, MARYLAND WOOD PRESERVATION No Drawing. Application filed July 25, 1924, Serial No. 728,177.. Renewed April 8, 1837.

(GRANTED UNDER THE ACT OF MARCH 3, 1883, AS AMENDED APRIL 30, 1828; 870 0. G. 757) The invention described herein may be nianu'laeturcd and used by or for the Govern ment for Government purposes, without the payment to me of any royalty thereon.

This invention relates to the preservatlon of wood and has more specific application to the treatment of wood which is exposed to sea water and the action of wood-boring organ isms, particularly limnoria and ship-Worms belonging to the class of marine borers. The

invention is also applicable to the treatment of wood for protection against attack from insects, fungi, dry rot, etc.

Among the objects of this invention is to rovide a material which may be employed or effectively preserving the wood in a manner that is eflicient and easy to operate and which will render the wood serviceable for prolonged periods of time.

A further object of this invention is to provide a composition for treatin wood, the composition comprising an oil w iich is practically immiscible with water and having dissolved therein an organic compound which is toxic to wood-boring organisms particularly of the character heretofore described.

Other, further and more specific objects of this invention will become readily apparent to persons skilled in the art from a consideration of the following description.

In applying the preservative material to wood, in order to allow the impregnating material to penetrate the wood, air and moisture contained in the wood is wholly or in part removed by a preliminary treatment. This allows the preservative to either coat the wood fibres or the impregnation may be carried on so as to completely fill the pores. A portion of the original moisture of the wood may be removed either by seasoning or air drying and the actual impregnation accomplished by using any of the standard processes employing heat, pressure or vacuum or a combination of two or more of these agents.

In carrying out my invention I treat the wood with an impregnating material comprising a solution of an Oil which 1s practically immiscible with water and containing a toxic organic material dissolved therein, the toxic material being relatively sparingly solable in water. The solubility of the toxic material in cold water should be only slightly in excess of the minimum toxic concentration for the organisms against attack by which the wood is being treated. It is to be understood that the solubility of the toxic agent in the water will increase with rise in temperature, but in order that it may be efl'ective under all conditions to which it is exposed while in use, it is essential that its solubility under the least favorable conditions, thatis when in cold water, should be sufiicient to provide a toxic zone of suflicient concentration for effective action upon the organisms. I have found, however, that such concentration in the low temperatures need not materially exwill not eifectively attack the wood.

The oil serves as a carrier for the toxic material and suitable oils for this purpose are crude petroleum oil, tar oil, etc. Other carriers, for example water gas tar and crudecoal tar may also be employed. I prefer however to use petroleum oil.

The oil carrier reduces the solubility of the toxic material in cold water to a point which is just suflicient to produce in the water in contact with the oil a lethal concentration for the wood-boring organisms. The concentration depends upon the partition'eoeflicient between the oil and the water. This results in a toxic concentration always being present in the immediate vicinity of the treated wood and in the case of marine piling the sea water in the immediate zone of the piling is rendered toxic to the marine borers. The oil also serves to prevent excessive leaching of the toxic material from the wood by the sea water, thereby prolonging the life of the toxic material in the wood. The oil further serves to retard or entirely prevent penetration of the water into the wood.

As toxic materials I prefer to use certain arsenical aromatic compounds such as phenyl- 5 dichlorarsine, phenylarsenous oxide, nitrophenylarsenous oxide, diphenylchlorarsine, diphenylaminechlorarsine, diphenylarsenous oxide, diphenylaminearsenous oxide, dichlordivinylarsenous oxide, etc. The quantity of toxic material dissolved in the oil carrier may vary from a trace up to several percent. Ordinarily it serves no economic purpose to use solutions containing more than 5% of toxic material. In using petroleum oil as a carrier, I prefer to use a solution containing 1% of the toxic material.

The solubilities at about- C. of the arsenical aromatic compounds mentioned above, expressed in parts per 100,000 parts of 20 sea water, are as follows:

Parts Phenyldichlorarsine 60 Phenylarsenous oxide 60 Diphenylchlorarsine 10 Diphenylarsenous oxide 9 Diphenylaminechlorarsine 0.8 Diphenylaminearsenous oxide 0.7

A specific example of carrying out my invention is as follows: The wood is first evacuated by removing the air and moisture from the pores, and a solution of petroleum oil and ph'enyldichlorarsine, containing about 1% of the latter, is forced into the more or less evacuated pores by means of pressure.

The amount of impregnating solution for protecting the timberfrom attack by marine borers will vary from 5 to lbs. per cubic foot of the wood, depending upon the toxic concentration of the impregnating solution and also to a large extent upon the location of the marine structure. Owing to the partition coefiicient between water and the oil carrier for the toxic employed, the impregnating solutions containing lower percentages of toxic material will not be relieved of the toxic material as readily as those containing the higher percentages of toxic. Other things being equal, the solutions with the higher ratios of oil to toxic material afford greater protection against excessive leaching of the toxic from the wood and the oil carrier and also admit of more uniform penetration and distribution of the preservative throughout the wood. Owing to the great toxicity in ex tremely low concentrations of the toxic agents heretofore described, the use of the high ratios of oil to toxic affords an effective means of economizing in the toxic. since it is not of material advantage that the toxicity of the water in the immediate vicinity of the wood be in substantial excess of the minimum toxic concentration for the organisms.

The intensity of attack by the marine borers 65 depends upon the length of the breeding season for the borers. This breeding season takes place only during the warm Weather, and when the weather becomes cold it is not necessary that there should be much solution of the toxic in the water. Hence, where the m piling is placed in warmer climates the ratio of impregnant to the treated wood should be greater than in colder climates.

In treating Wood, such as ties, posts, marine timber, etc., by my invention as herein described, I am enabled to regulate with reasonable certainty and precision the life of the treated wood under conditions of use. By determining the solubility of the toxic material in the carrier and water and regulating the quantity of the impregnating solution for the wood, I am able to obtain a treated product where the service afforded by the preservative in the wood will closely approximate the life of the wood as governed by the mechanical 85 uses to which the wood is applied. My in vention thus affords a means of treating the wood with sutficient preservative for protecting against the wood-boring organisms without necessitating the use of an excess quantity of preservative, as is required by the processes heretofore practiced in order to assure that sufficient preservative be present for the piotection of the wood during its mechanical The present invention is not limited to the specific details set forth in the foregoing examples which should be construed as illustrative and not by way of limitation, and in view of the numerous modifications which 100 may be effected therein without departing from the spirit and scope of this invention, it is desired that only such limitations be imposed as are indicated in the appended claims.

I claim as my invention:

1. In a wood preservative, a solution in petroleum oil of an arsenical, organic compound, toxic to marine borers and having a solubility of 0.7 to 60 parts in 100,000 parts of 1 sea water at 20 C.

2. In a wood preservative, a solution in petroleum oil of an arsenic derivative of an aromatic compound, toxic to marine borers and having a solubility of 0.7 to 60 parts in 100,000 115 parts of sea water at 20 C.

3. In a wood preservative, a solution in petroleum oil of an arsenical, organic compound, toxic to marine borers and having a solubility of 0.7 to 10 parts in 100,000 parts of 190 sea water at 20 C.

4. In a wood preservative, a solution in petroleum oil of an arsenic derivative of an aromatic compound, toxic to marine borers and having a solubility of 0.7 to 10 parts in 125 100,000 parts of sea water at 20 0.,

5. As an article of manufacture, wood impregnated with a solution in petroleum oil of an arsenical, organic compound, toxic to wood-boring organisms and ha ing a solubility of 0.7 to 60 parts in 100,000 parts of sea water at 20 C.

6. As an article of manufacture, wood impregnated with a solution in petroleum oil of an arsenic derivative of an aromatic compound, toxic to wood-boring organisms and having a solubility of 0.7 to 60 parts in 100,000 parts of sea water at 20 C.

7. As an artlcle of manufacture, wood impregnated with a solution in petroleum oil of an arsenical, organic compound, toxic to' wood-boring organisms and having a solubility of 0.7 to 10 parts in 100,000 parts of sea water at 20 C.

8. As an article of manufacture, wood impregnated with a solution in petroleum oil of an arsenic derivative of an aromatic compound, toxic to wood-boring organisms and having a solubility of 0.7 to 10 parts in 100,000 parts of sea water at 20 C.

HOWARD S. MOQUAID. 

